Removable baffles for mixing vessel

ABSTRACT

A mixing vessel may include a container having a bottom with a removable plate fixed to the bottom. The removable plate may include one or more slots for inserting baffles therein. A flexible baffle insert may include a retaining band having inner and outer opposing surfaces. A plurality of baffles may extend inwardly from the inner surface of the retaining band.

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or forthe Government of the United States of America for Governmental purposeswithout the payment of any royalties thereon or therefor.

FIELD OF THE INVENTION

The invention relates, in general, to mixing vessels, and, inparticular, to mixing vessels with easily interchangeable baffles.

BACKGROUND OF THE INVENTION

Mixing vessels may be used in a variety of commercial and industrialprocesses. A variety of materials may be mixed in a mixing vessel.Different materials and different processes may require differentamounts of shear and flow patterns to properly mix the ingredients,maintain the ingredients in suspension, and circulate the ingredientswithin the vessel. The size, shape, location, orientation, androtational speed of the mixing vessel impeller may be factors inproducing specific flow patterns tailored for a particular product.

A mixing vessel without baffles may not produce enough shear orturbulence to mix the ingredients. Therefore, many mixing vessels mayinclude fixed baffles that may influence the mixing action and flowpatterns. The number, size, location and geometry of baffles may varywidely, generating both localized high shear between the baffle andimpeller blades, and generating circulating currents that may promotethe homogeneity and suspension of ingredients. A configuration ofimpeller and baffles that may be optimized to produce one product may beunsuitable for a different product.

The flow patterns and circulating currents may also be influenced by theshape of the vessel itself. Typically, a vessel having a concave bottommay produce better vertical dispersion because the liquid may be slungout radially from the impeller and may be gently turned upward when theliquid moves toward the vessel wall. Flat-bottomed mixing vessels maynot do this function nearly as well, and may have very poor flowpatterns. Acceptable flow patterns and methods of mixing a material maybe discovered by adding and experimenting with various types of baffles.

In the past, new mixing vessels with optimized geometry were constructedfor, and exclusively dedicated to, a specific process or product. As analternative, existing plain mixing vessels that were, at first,completely unsuitable for a particular process, were retrofitted byadding permanently welded baffles. In such mixing vessels, it may berelatively easy and common practice to make small variations in themixing action and fine tune it to slightly different processes bychanging the impeller or its rotational speed. Changing the baffling mayhave a much larger effect, but it may be costly to construct a newmixing vessel each time one wishes to alter a baffle arrangement. It mayalso be costly to remove welded baffles and reweld new baffles in amixing vessel.

In a manufacturing scenario where more than one product is made, forinstance, the manufacturer may set up a single production line, andsimply switch baffles in the mixing vessels. In a research anddevelopment scenario, the effect that each element of geometry has onthe mixing process itself, or the effect that each element of geometryhas on the quality of the product being produced, may be explored usingmany physical variations. Baffles that are easily removed and replacedin a mixing vessel may save time, money, and storage space (for multiplevariations of mixing vessels), and simplify cleaning and repair ofbaffles. Thus, a need exists for mixing vessels having easilyinterchangeable baffles.

In some cases, such as laboratory bench top and glassware size vessels,a mixing vessel having the desired baffle arrangement may not beavailable commercially. Formulations and mixing procedures for productsmay be developed and tested in both small and medium scale laboratorymixers before transitioning to high rate production in full size mixingvessels. A manufacturing plant that uses 3000 gallon baffled mixers mayhave a laboratory where procedures are developed in quart or gallonsized mixers. Thus, there is a need to be able to adapt standardlaboratory glassware mixing vessels, for instance, into scale models oflarger mixing vessels, by adding baffle kits.

SUMMARY OF THE INVENTION

An aspect of the invention may be a mixing vessel including a containerhaving a bottom. The bottom may include a removable plate fixed thereto.The removable plate may include at least one slot formed therein. Abaffle may be inserted in at least one slot.

Another aspect of the invention may be a flexible baffle insertincluding a retaining band having inner and outer opposing surfaces, anda plurality of baffles extending inwardly from the inner surface of theretaining band. Each baffle may include first and second edges proximatethe inner surface of the retaining band. The first proximate edge mayform a support joint with the inner surface of the retaining band andthe second proximate edge may be displaced inwardly from the firstproximate edge.

A further aspect of the invention may be a mixing vessel including acontainer having a bottom and a generally circular side wall, and aflexible baffle insert disposed in the container.

Another aspect of the invention may be a method of making a flexiblebaffle insert. The method may include providing a thin, flexiblematerial having a retaining band and a plurality of baffles, where theretaining band and the baffles are substantially coplanar. The relatedmethod may include bending the baffles along an edge such that thebaffles are angled with respect to the retaining band.

The invention will be better understood, and further objects, features,and advantages thereof will become more apparent from the followingdescription of the exemplary embodiments, taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily to scale, like orcorresponding parts are denoted by like or corresponding referencenumerals.

FIG. 1 is a side view of a mixing vessel without baffles.

FIG. 2 is a top view of FIG. 1.

FIGS. 3A and 3B are top and side views, respectively, of a removableplate.

FIG. 4 is a top view of the mixing vessel of FIG. 2 with the removableplate removed.

FIGS. 5A and 5B are side and end views, respectively, of an embodimentof a baffle.

FIGS. 6A and 6B are side and end views, respectively, of anotherembodiment of a baffle.

FIGS. 7A, 7B, and 7C are perspective views, respectively, of anembodiment of an independent baffle, an embodiment of a baffle spacer,washer, and fastener, and an embodiment of an independent baffleassembly, prior to disposition in a mixing vessel.

FIG. 8 is a perspective view of a removable plate with baffles as shownin FIGS. 5A and 5B, disposed on the bottom of a mixing vessel.

FIG. 9 is a perspective view of a removable plate with baffles as shownin FIGS. 6A and 6B, disposed on the bottom of a mixing vessel.

FIG. 10 is a perspective view of independent baffles as shown in FIG.7C, disposed on the bottom of a mixing vessel.

FIGS. 11A and 11B are side and top views, respectively, of a mixingvessel with an embodiment of a removable baffle assembly disposedtherein.

FIG. 12 is a top view of an embodiment of a flexible baffle insert,prior to disposition in a mixing vessel.

FIG. 13 is a view along the line 13-13 of FIG. 12.

FIG. 14 is a side view of a baffle insert, prior to forming.

FIGS. 15A and 15B are side and top views, respectively, of a mixingvessel with an embodiment of a flexible baffle insert disposed therein.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a side view of a mixing vessel 10 and FIG. 2 is a top view ofthe mixing vessel 10 shown in FIG. 1. Mixing vessel 10 may be one pieceor it may be an assembly including, for example, a container 12 having abottom 14, side walls 18, and a generally open interior 16. The bottomof the mixing vessel may have any contour or it may be flat as shown inFIG. 1. The shape and location of the impeller 15 may be varied to suita particular process.

FIGS. 3A and 3B are top and side views, respectively, of one exemplaryembodiment of a removable plate 20. Plate 20 may include at least onefastener opening 26 formed therein. Plate 20 may include at least oneslot 22 formed therein for receiving a baffle. A periphery of plate 20may include a beveled edge 42. The shape of the plate 20 and thelocation of the fastener openings 26 may be varied to suit a particularprocess.

FIG. 4 is a top view of the mixing vessel 10 of FIG. 2 showing fasteneropenings 28 that may be formed in bottom 14. Fastener openings 26 inplate 20 may correspond to fastener openings 28 in bottom 14.

FIGS. 5A and 5B are side and end views, respectively, of an embodimentof a baffle 30. Baffles 30 may have any shape that is needed for aparticular process. Baffle 30 may include a tab portion 32 and a bodyportion 34. Tab portion 32 may be inserted into slot 22 in plate 20. Tabportion 32 and slot 22 may form, for example, a press fit, and may bepermanently joined by welding, brazing, or any other joining process.Tab portion 32 and body portion 34 may be substantially planar.

FIGS. 6A and 6B are side and end views, respectively, of anotherexemplary embodiment of a baffle 36. Baffle 36 may include a tab portion40 and a body portion 38. Tab portion 40 may be inserted into slot 22 inplate 20. Tab portion 40 and slot 22 may form, for example, a press fit,and may be permanently joined by welding, brazing, or any other joiningprocess. Body portion 38 may be angled with respect to tab portion 40 byangle A. Angle A may be any angle that is needed for a particularprocess. In the embodiment of FIG. 6B, angle A is about 15 degrees.

FIG. 7A is an embodiment of an independent baffle 42. Baffle 42 mayinclude a tab portion 43 and a body portion 44. Tab portion 43 mayinclude a fastener opening 46 that corresponds to fastener openings 28on bottom 14 of the mixing vessel of FIG. 4. Baffles 42 may have anyshape that is needed for a particular process.

FIG. 7B shows perspective views of a fastener 24, a washer 47, and aspacer 48 of thickness 49. The washer 47 and the spacer 48 may includefastener openings similar to the fastener opening 46 in tab 43 of baffle42.

FIG. 7C is a perspective view of a baffle assembly 45 including a spacer48, a baffle 44, a washer 47 and a fastener 24, prior to disposition onbottom 14 of the mixing vessel of FIG. 4.

For clarity, in FIGS. 8, 9, and 10, the side walls 18 of container 12are not shown. FIG. 8 is a perspective view of a container bottom 14having a removable plate 20 with baffles 30 as shown in FIGS. 5A and 5B.FIG. 9 is a perspective view of a container bottom 14 having a removableplate 20 with baffles 36 as shown in FIGS. 6A and 6B. Removable plate 20may be fixed to bottom 14 with fasteners 24.

FIG. 10 is a perspective view of a container bottom 14 having baffleassemblies 45, as shown in FIG. 7C, disposed therein. The baffleassemblies 45 may not require a removable plate 20, and may be disposedanywhere inside the mixing vessel where suitable fastener openings 28are located. Baffles assemblies 45 may be rotated to any angle about theaxes of fasteners 24 as needed to suit a particular process. The spacerthickness 49 may create a gap between the bottom of the assembly 45 andthe surface having the fastener opening 28, which may be varied asneeded to suit a particular process. The washer 47 and spacer 48 shownin FIG. 7C may form a seal for the fastener openings 28 in bottom 14,shown in FIG. 4.

Any number of baffles may be used as needed for a particular process. InFIGS. 8, 9, and 10, eight baffles are shown.

FIGS. 11A and 11B are side and top views, respectively, of the mixingvessel 10 of FIG. 2 including one exemplary embodiment of a removablebaffle assembly 19. Assembly 19 includes removable plate 20 and baffles30, retained by fasteners 24.

FIG. 12 is a top view of a portion of a flexible baffle insert 52.Insert 52 may include a retaining band 56 having inner and outeropposing surfaces 60, 62, respectively. A plurality of baffles 58 mayextend inwardly from the inner surface 60 of the retaining band 56.Baffles 58 optionally may be spaced substantially equally on theretaining band 56. The total number of baffles 58 and their shape may bevaried as needed for a particular process. A pair of tabs 68 may bedisposed on opposite ends of the retaining band 56 and angled inwardly.

As best seen in FIGS. 12, 15A, and 15B, each baffle 58 may include afirst edge 64 proximate the inner surface 60 of the retaining band 56and a second edge 66 proximate the inner surface 60 of the retainingband 56. First edge 64 may be more proximate inner surface 60 thansecond edge 66. First (proximate) edge 64 may form a support joint withthe inner surface 60 of the retaining band 56. Second (proximate) edge66 may be displaced inwardly from the first (proximate) edge 64. Thedisplacement of the second (proximate) edge 66 away from the first(proximate) edge 64 may provide a gap or open area 80 between a portionof baffle 58 and the side wall 76 of container 74. Gap 80 may be helpfulin some mixing processes.

Each baffle 58 may include an upper edge 70 that forms an angle B (FIG.12) with respect to the inner surface 60 of the retaining band 56. InFIG. 12, the angle B is about 90 degrees, for example. However, angle Bmay be other than ninety degrees. Each baffle 58 may include a loweredge 72 (see FIG. 14, also) that forms an angle D between the lower edge72 of the baffle 58 and the inner surface 60 of the retaining band 56.When angles B and D are the same, the baffle 58 will be verticallyoriented.

In the exemplary embodiment shown in FIGS. 12, 15A, and 15B, angle D islarger than angle B, such that baffle 58 is “slanted.” In the Figures,in an exemplary embodiment, angle B is about 90 degrees and angle D isabout 110 degrees. Other exemplary values for angles B and D may beused. FIG. 13 is a view along the line 13-13 of FIG. 12 showing theslant of baffle 58 in a different perspective. Angle C in FIG. 13 isabout 80 degrees, for example. Other exemplary values for angle C may beused.

FIG. 14 is a side view of a flexible baffle insert 52, prior topreforming. In FIG. 14, baffles 58 are substantially coplanar withretaining band 56. Baffles 58 and retaining band 56 may be formed from asingle sheet of material such as, for example, spring-temper brass shimstock. The shim stock may be, for example, about 0.015 inches thick.After stamping the shim stock to produce the configuration shown in FIG.14, baffles 58 may be bent along edges 64 such that the baffles 58 areangled with respect to the retaining band 56. As noted above, baffles 58may be bent so that upper edge 70 forms an angle B with retaining band56. In FIG. 12, angle B is about 90 degrees, but other angles may beused. After bending baffles 58, each baffle 58 includes an edge 66proximate the retaining band 56, but displaced away from the retainingband 56, that is, edge 64 is more proximate the retaining band 56 thanedge 66.

If one desires a baffle insert 52 with baffles 58 that are not vertical,then one may further bend the baffles 58. One may further bend baffle 58such that upper edge 70 of the baffle 58 forms an angle B with respectto the retaining band 56 that is different than an angle D of a loweredge 72 of the baffle 58 with respect to the retaining band 56. FIGS.12, 13, 15A, and 15B show an embodiment where angle D is larger thanangle B.

The retaining band may be bent into a curve approximately as shown inFIG. 12. This curve may have a radius that is larger than the radius ofthe interior of the mixing vessel 50. The retaining band 56 may beflexed into a circular shape by squeezing together the pair of tabs 68disposed on opposite ends of the retaining band 56. Insert 52 may beinserted into a mixing vessel 50, and the pair of tabs 68 released. Asthe retaining band 56 expands, it grips the side wall 76 as shown inFIGS. 15A and 15B. In an iterative process, the insert 52 may beremoved, its curvature may be adjusted, and it may be reinserted intovessel 50, until no gaps are visible between the retaining band 56 andthe side wall 76.

FIGS. 15A and 15B are side and top views, respectively, of a mixingvessel 50 with a flexible baffle insert 52 disposed therein. Mixingvessel 50 may include a container 74 having a bottom 78 and a generallycircular side wall 76. Mixing vessel 50 may have an impeller 54 disposedtherein. Container 74 may be any type of container. FIGS. 15A and 15Bshow a standard, plain Groen jacketed container, by way of example, witha flexible baffle insert 52 therein.

Finally, any numerical parameters set forth in the specification andattached claims are approximations (for example, by using the term“about”) that may vary depending upon the desired properties sought tobe obtained by the present invention. At the very least, and not as anattempt to limit the application of the doctrine of equivalents to thescope of the claims, each numerical parameter should at least beconstrued in light of the number of significant digits and by applyingordinary rounding.

What is claimed is:
 1. A mixing vessel, comprising: a container having abottom, the bottom includes a removable plate fixed to the bottom, andthe removable plate includes a plurality of slots and a plurality offirst fastener openings both formed therein; a plurality of baffles,each baffle being inserted in respective slots of said plurality ofslots; and an impeller including an axis, wherein a portion of thebottom of the container, which is beneath the removable plate, includesa corresponding plurality of second openings therein, and wherein saidplurality of baffles are inserted in the removable plate to be situatedconcentric about the axis of the impeller.
 2. The mixing vessel of claim1, wherein the removable plate includes a beveled edge.
 3. The mixingvessel of claim 1, wherein each of said plurality of baffles includes atab portion for insertion in one of the plurality of slots.
 4. Themixing vessel of claim 1, wherein said plurality of baffles is comprisedof eight baffles.
 5. The mixing vessel of claim 1, wherein each of saidplurality of baffles includes a tab portion for insertion in one of theplurality of slots, and wherein the tab portion and said at least oneslot form a press fit.
 6. The mixing vessel of claim 1, wherein each ofsaid plurality of baffles includes a tab portion for insertion in one ofthe plurality of slots, and wherein each of said plurality of bafflesincludes a body portion.
 7. The mixing vessel of claim 1, wherein eachof said plurality of baffles includes a tab portion for insertion in oneof the plurality of slots, wherein each of said plurality of bafflesincludes a tab portion for insertion in one of the plurality of slots,wherein each of said plurality of baffles includes a body portion, andwherein the body portion of each of said plurality of baffles issubstantially planar with the tab portion of each of said plurality ofbaffles.
 8. The mixing vessel of claim 1, wherein each of said pluralityof baffles includes a tab portion for insertion in one of the pluralityof slots, wherein each of said plurality of baffles includes a tabportion for insertion in one of the plurality of slots, wherein each ofsaid plurality of baffles includes a body portion, and wherein the bodyportion of each of said plurality of baffles is angled with respect tothe tab portion of each of said plurality of baffles.
 9. A mixingvessel, comprising: a container having a bottom, the bottom includes aremovable plate fixed to the bottom, and the removable plate includes aplurality of slots and a plurality of first fastener openings bothformed therein; a plurality of baffles, each baffle being connected torespective said plurality of first fastener openings; an impellerincluding an axis; and a plurality of fasteners, wherein a portion ofthe bottom of the container, which is beneath the removable plate,includes a corresponding plurality of second openings therein, whereinsaid plurality of fasteners are disposed in the plurality of firstfastener openings in the removable plate and the corresponding pluralityof second openings in the portion of the bottom of the container tothereby secure the removable plate to the bottom of the container.